03768nas a2200169 4500008004100000245013500041210006900176520316700245653002403412653002503436653002103461653001403482653001703496100002003513700001703533856004803550 1984 eng d00aThe role of two-tone suppression in song coding by ventral cord neurones in the cricket Teleogryllus oceanicus (Le Guillou)0 arole of twotone suppression in song coding by ventral cord neuro3 a

1.The calling, courtship and aggression songs ofT. oceanicus have distinctive temporal patterns but their spectral compositions are very similar: the carrier frequency occurs around 4.5 kHz and harmonics occur which extend above background noise level up to at least 40 kHz (Fig. 1).

2.Units were recorded in the cervical connectives which responded to sound frequencies over the range from 1 kHz to at least 40 kHz. The sensitivities of some of the high frequency units were comparable to, or exceeded, the sensitivities of the units responding to the carrier frequencies of the species songs (Fig. 2).

3.At the level of the neck connectives, units responding to the range from 10 kHz to 40 kHz could be divided, on the basis of their prothoracic morphology and physiology, into Through Neurones and Ascending Neurones. All the recorded neurones showed two-tone suppression effects but they varied in their degree of susceptibility to suppression. Frequencies in the range 4–5 kHz were most effective in producing suppression of the responses to high frequency tones (Figs. 5, 6).

4.The two identified Ascending Neurone types had similar morphologies in the prothoracic ganglion (Fig. 3). ANA showed tonic responses to pure tones in the frequency range from 10 kHz to 40 kHz. Below 10 kHz high intensity inhibition of the response occurred and the latency increased from about 15 ms for an 18 kHz tone pulse, to about 55 ms for a 4.5 kHz tone (Fig. 4). ANB responded with 1–3 spikes to stimuli in the frequency range from 7 kHz to 40 kHz. The response latency to an 18 kHz tone pulse was about 15 ms. No responses were obtained to 50 ms stimuli in the range from 2 kHz to 7 kHz (Fig. 6). However, considerable rebound activity was produced in response to 4.5 kHz stimuli of 200 ms or more; the latency of the rebound to 200 ms stimuli was about 400 ms (Fig. 6C).

5.ANA neurones responded to the syllables of the natural songs (Fig. 7), clearly coding the temporal patterns of the three songs. Cutting the contralateral leg nerve resulted in no detectable change in the neurone's response pattern. ANB neurones responded only during the intervals between chirps and during pauses within chirps. A long period of bursting activity occurred at the end of each song sequence (i.e. 3 chirps). This rebound activity may be the result of extreme inhibition caused by the CF of the songs (Fig. 7).

6.Synthesised natural songs (Fig. 1 E) with the correct temporal parameters but filled with 4.5 kHz alone, 18 kHz alone or a combination of 18 kHz and 4.5 kHz, were produced to investigate the role of two-tone suppression phenomena in song coding. The responses of both ANA and ANB (Fig. 8) showed the interaction of excitatory and inhibitory inputs to these units during the coding of the species songs.

7.Two-tone inhibition effects are advanced as the basic mechanism for the accurate coding of temporal characteristics in the songs ofT. oceanicus. Two different strategies for the recognition of species song types in crickets are advanced.

10aHigh Frequency Tone10aProthoracic Ganglion10aRebound Activity10aSong Type10aVentral Cord1 aHutchings, Mary1 aLewis, Brian uhttp://link.springer.com/10.1007/BF0060539502044nas a2200229 4500008004100000022001300041245010800054210006900162260001600231300001400247490000700261520134900268653002501617653001201642653001701654653001001671653001401681100001901695700001801714700001701732856006501749 1984 eng d a0022191000aProcessing of vibratory and acoustic signals by ventral cord neurones in the cricket Gryllus campestris0 aProcessing of vibratory and acoustic signals by ventral cord neu cJan-01-1984 a575 - 5850 v303 a

The responses of single vibratory receptors and ascending ventral cord interneurones were studied extracellularly in Gryllus campestris L. The physiology of the vibration receptors resembled those found in tettigoniids and locusts. The frequency responses of the subgenual receptors provide two possible cues for central frequency discrimination: differences in mean tuning between groups of receptors in the different leg pairs and a range of receptors tuned to different frequencies within one subgenual organ.

Most of the ascending vibratory interneurones were highly sensitive in either the low or high frequency range. Broadbanded neurones were less sensitive. The characteristic sensitivity peaks of these units are due mainly to receptor inputs from a particular leg pair, although most central neurones receive inputs from all 6 legs. Only one neurone type, TN1 received excitatory inputs from both auditory and vibratory receptors; its responses were greatly enhanced by the simultaneous presentation of both stimulus modes. The responses to sound stimuli of AN2, on the other hand, were inhibited by vibration. No other auditory interneurones investigated were influenced by inputs from vibration receptors. Central processing of vibratory information in the cricket is compared with that of tettigoniids and locusts.

10acentral coprocessing10acricket10ainterneurone10asound10avibration1 aKühne, Roland1 aSilver, Susan1 aLewis, Brian uhttp://linkinghub.elsevier.com/retrieve/pii/0022191084900866